LDAP listen to multiple interfaces?

I have a server with 2 network interfaces. One is connected to the Internet and the other is connected to a private Intranet.

Currently, Zimbra is configured to answer LDAP requests on the Internet interface. Is there a way to have it answer requests on the Intranet interface too? I know if I change the "ldap_url" attribute with zmlocalconfig, I can change which interface it answers on, but I cannot seem to add a second "ldap_url" attribute.

I realize this is an older thread, but I was looking for the same answer myself. I ended up editing /opt/zimbra/conf/localconfig.xml and changing the ldap_url variable to ldap://0.0.0.0:389 which forces slapd to listen on all interfaces. I hope that helps somebody in the future.